This invention relates to a device for separating warp yarns on a face-to-face weaving machine, comprising at least one separating means and a holding device provided to keep the separating device at a holding height and to adjust this holding height.
On a face-to-face weaving machine two backing fabrics are woven simultaneously above one another. For that purpose backing warp yarns (for instance tension warp yarns and binding warp yarns) are provided on the weaving machine. During consecutive weft insertion cycles an upper shed is formed between a number of backing warp yarns, and a lower shed is formed between a number of other backing warp yarns. This shed forming occurs by means of shed forming means that can bring the warp yarns into two different positions. Into these sheds each time a weft yarn is inserted during the consecutive cycles.
The ground warp yarn supply is provided on warp yarn beams, for instance a tension warp yarn beam and a binding warp yarn beam. From those beams the backing warp yarns are conducted to the weaving machine. Before the yarns reach the shed forming means they are separated into two layers situated above one another. An upper layer with the backing warp yarns, which are needed to weave the upper backing fabric and a lower layer with the backing warp yarns, which are needed to weave the lower backing fabric.
It is generally known to keep these two layers of backing warp yarns separated from one another by means of two yarn separating cylinders. These cylinders are situated above one another between the two yarn layers, the warp yarns of the upper layer running over the top of the upper yarn separating cylinder, and the warp yarns of the lower layer touching the lower side of the lower yarn separating cylinder. In this manner, the warp yarns of the two layers are kept separated from each other at a vertical distance and are kept well apart.
In order to prevent the backing warp yarns from becoming slack in one of their two positions, each yarn separating cylinder has to be installed exactly in the bisector plane of the respective shed. It is known to attach these yarn separating cylinders to the weaving machine by means of a holding device enabling the holding height to be adjusted and to be adjusted in the warp-direction.
In a known adjustable device to separate the yarns on a face-to-face weaving machine the separating cylinders are connected to respective holders, which extend horizontally in the warp-direction towards the yarn beams. These holders are provided with a number of holding bores separated from one another in the warp-direction. A vertical cylindrical bar, which is fixed to the frame of the weaving machine, extends through a holding bore of both holders. In this manner, the holders are provided on the bar in a slidable manner and they may be attached to this bar at a height as desired by means of a clamp joint. These clamp joints are fixed by means of a bolted joint. The position of the separating cylinders is adjustable in the warp-direction by using another holding bore.
However, this known device has a number of important disadvantages. When adjusting a new holding height of the separating cylinders, after loosening the clamp joint, the holder remains in its original position on the vertical cylindrical bar because of its self-clamping action. Only when driving a wedge into the clamp opening, the clamp joint opens all of a sudden and the separating cylinder will move downwards or upwards under the influence of its own weight and/or under the influence of a tractive force, exerted on the separating cylinder by the warp yarns. Because of this, the original adjustment will be totally lost. When adjusting a separating cylinder at a new holding height it is however desirable that the original holding height can be used as a reference. For that purpose, with this device, the original position should be marked or measured first before loosening the clamp joint. Than the new position can be compared with the original position either by referring to this marking, or by measuring once again the new position and by comparing the new measured value with the measured value of the original position. Therefore adjusting the separating cylinders is a complicated and time-consuming job and, moreover, it cannot be done with great precision.
Moreover, when loosening the clamp joint by driving in a wedge, there is always a risk that the separating cylinders start falling downwards or moving upwards under the influence of their own weight and/or under the influence of the tractive force exercised on the separating cylinders by the backing warp yarns. This movement of the separating cylinders can be dangerous, so that the person who carries out this job should be prepared for a temporarily unsafe situation.
The purpose of this invention is to provide a device to separate the warp yarns on a face-to-face weaving machine by means of which the above-mentioned disadvantages can be remedied and which therefore will enable the holding height to be adjusted in a simple and exact manner under safer conditions.
According to this invention this goal is achieved by providing a device to separate warp yarns on a face-to-face weaving machine, which has the characteristics mentioned in the first paragraph of this description and the holding device of which comprises a threaded adjusting means, whereas the adjusting means is provided in such a manner that its rotation causes the separating means to be moved, because of which the holding height is changed and whereas the adjusting means can maintain the separating means at the holding height adjusted.
With this device, the holding height of the separating means can be changed by rotating a threaded adjusting means. A similar adjusting is particularly simple and can be done with great precision. Because the adjusting means is also provided to hold the separating means at the adjusted height, during this adjusting operation, any unwanted and dangerous upward and downward movements of the separating means, under the influence of its weight and/or the tractive force of the warp yarns, are avoided. Therefore, with the device according to this invention, adjusting the holding height can be done in a far more exact and simple manner, and under safer conditions than with the known devices.
In a preferred embodiment of this invention the adjusting element is attached rotatably at a fixed height and this element is provided to move the separating element by means of its screw thread.
For instance, the adjusting element may be carried out as an adjusting element (for instance an adjusting spindle) attached at a fixed height with a threaded handle extending vertically, engaging in a bore of the separating element or of a part connected to it, so that the rotation of the adjusting spindle in the bore causes the adjusting means to be moved up or down (depending on the sense of rotation).
Preferably, the holding device is also provided to adjust the position of the separating element in the warp-direction.
The holding device can also be carried out with a movable intermediate part to which the separating means is connected, the position of the separating element being adjustable in the warp-direction with respect to the intermediate part and the adjusting means being provided to move the intermediate part in order to adjust the holding height. Thus a simple holding device is obtained where adjusting the height and adjusting in the warp-direction can occur on the same adjusting point.
In a particular embodiment the holding device comprises also a fixedly attached support, whereas the adjusting means makes a connection between the support on the one hand and the separating means, or a part connected to this separating means, on the other hand.
If the intermediate part is attached in a movable manner on a part of the support extending in a practically vertical direction a device is obtained with a holding height that can be adjusted in a very easy and accurate manner.
In a very advantageous embodiment of this invention reference marks, such as a graduation for instance, are provided on a part of the holding device to be fixedly attached to it, in order to determine or read the position of the intermediate part with respect to the support. With these reference marks (for instance dots, lines, numbers, letters) or graduation, the corresponding position of the intermediate part can be easily determined or read for the different holding heights. For instance, this position can be read very easily on a graduation with numbers. Because of this it will become very simple to adjust a holding height without measuring or without any other means, one or more other holding heights being used as a reference. If the distance between the reference marks has been chosen to be sufficiently small, this will also enable the holding height to be adjusted with far greater precision than with the other devices known at this moment.
Preferably the holding means comprises a support connected to the separating means which is connected to the said intermediate part in a manner slidable in the warp-direction. Because of this, adjusting in the warp-direction can be carried out in a more simple manner and with a greater number of different positions than with the known devices mentioned above.
It is further very advantageous and useful when reference marks, such as for instance a graduation, is provided on the holder in order to determine or to read the position of the holder with respect to the intermediate part. This also enables to determine or to read the corresponding position of the holder for different positions in the warp-direction. Because of this, adjusting in the warp-direction may be realized in a more accurate and simple manner. Also when adjusting in case one or more other positions in the warp-direction should be used as a reference, this becomes very easy without measuring or any other means.
Preferably, the holding device further comprises also clamping means to maintain the intermediate part in a position adjusted with respect to the support and to maintain the holder in a position adjusted with respect to the intermediate part. Preferably these clamping means are bolts provided in a same clamping block with cover.
In a very preferred embodiment of the invention the intermediate part is crossed by a part of the support extending in a practically vertical direction and by a part of the holder extending in the warp-direction. Preferably, the said clamping means are provided at the intersection of these two parts crossing the intermediate part.
Preferably, the device according to this invention is carried out with two separating means and for each separating means a holding device having one or more of the particular characteristics mentioned above. Because of this the holding height of each separating means can be adjusted in a simple and accurate manner and without any safety risks, so that each yarn layer can be conducted over the respective separating means to the weaving machine at the ideal height. Then both holding devices can best be carried out with respective adjusting means and intermediate parts means working together with a common support.
Of course, a face-to-face weaving machine provided with a device to separate the warp yarns according to this invention is also within the scope of this invention.
The characteristics, advantages and particulars of this invention are further clarified in the more detailed description of an embodiment following hereafter. The only purpose of this description is to clarify the invention by means of an example and may in no way be considered as a limitation of the scope of this patent application.